You have periodontal disease caused by plaque build-up. You need to go to the dentist and get your teeth cleaned, and then start taking good care of them, or your teeth will eventually get loose, and can fall out. It does cause mouth odor and you don't want this.
Plaque build-up is caused by not brushing correctly or often enough. Food particles remain around the teeth working their way between your teeth and gums, causing swelling, redness, and bleeding. Brus, floss, and use listerine 2 X a day, it is very good for your gums. You cannot correct this on your own at this point, but a thorough cleaning by the dentist will remove it all, but then you have to keep up good oral hygiene.
Thank you.
Would this also be a symptom of STD ?